In the related art, there is a known structure in which a plurality of photoelectric conversion layers are laminated in order to improve the photoelectric conversion efficiency of a thin-film solar cell. For example, a tandem solar cell in which an amorphous silicon layer and a microcrystalline silicon layer are laminated is known. This tandem solar cell is formed by sequentially laminating a transparent electrode, an amorphous silicon layer, a microcrystalline silicon layer, and a back electrode on a light-transmitting substrate. There is a known technique for achieving a further improvement in photoelectric conversion efficiency by providing, between the amorphous silicon layer and the microcrystalline silicon layer, an intermediate contact layer that is electrically and optically connected thereto, causing part of the incident light to be reflected.
Such a tandem solar cell increases the voltage to obtain the desired voltage by connecting a plurality of photoelectric conversion cells in series. When a plurality of photoelectric conversion cells are connected in series, the back electrode and the transparent electrode are connected by forming a connecting groove that penetrates the amorphous silicon layer, the intermediate contact layer, and the microcrystalline layer, and this connecting groove is filled with the back electrode.
On the other hand, because the intermediate contact layer exhibits conductivity, when it is electrically connected to the connecting groove, which is filled with the back electrode, the electrical current generated in the amorphous silicon layer and the microcrystalline layer leaks to the connecting groove via the intermediate contact layer.
Thus, a technique for preventing current leakage from the intermediate contact layer to the connecting groove by separating the intermediate contact layer by means of laser processing has been proposed (see PTL 1 and PTL 2).